If you had lava and you poured it onto ice of the exact polar opposite temperature (similar to this) which one would win provided you have equal mass of each substance and exactly opposing temperatures.

I think I worded that badly, but you guys get the idea.

The ending temperature, I am guessing, would not result in the exact center, so one would essentially "win".

EDIT: I need to give a better design. The lava is to be poured as thin as possible to avoid the outside protecting the inside. It will be on a decline to avoid the lava collecting. There is exactly the same mass of ice and lava, steam lost to the process is just lost, if it makes ice inferior in this experiment so be it. Environmental factors are a controlled temperature room. Let's say the lava is 1,000 degrees Celsius, the ice would then be -1,000 degrees Celsius and the room this is done in is exactly 0 degrees Celsius.

Also, the experiment takes exactly 90 seconds, so the room has little to no effect on the temperature.

I am guessing the lava would win as I think it takes more energy to cool something as it does to warm it up. So it would expend the ice before the lava. Completely non-scientific guess, just a thought.